Prodn. of phosphoric acid with reduced inorg. impurities from crude phosphoric acid obtd. by decompsn. of an ore of phosphorus with sulphuric acid comprises extracting the crude acid with a 6-8C alkanol (I), washing the extra =4 times with water opt. contg. phosphoric acid, the total amt.of washing water beeing 20-50 pts. wt. per 100 pts. wt. phosphoric acid contained in the extract, and back extracting the washed extract with water to obtain aq. phosphoric acid with reduced inorg. impurities, which if desired may subsequently be concd. Pred. (I) is 3 or 5 methylhexanol. The process is simple and avoids the use of expensive metals. such as ion exchange resins.
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